> Just the idea that watching some ads in a search engine can fix the world, that's the problem I'm having an issue with.

I agree with you, it won't change the world. But again I think it's mainly just marketing. They do what they claim and they do seem to care about actually making a difference and are somewhat consistent with their efforts so I wouldn't call that "greenwashing". I don't think their efforts are minimal but what do I know about planting trees and stuff. You can check their youtube channel :

https://www.youtube.com/@Ecosia/videos